A run of an elevator car might be interrupted owing to a functional nonconformance in such a way that the elevator car becomes jammed at a point outside the exit floor, at which point the elevator passengers are not able the leave the elevator car. A functional nonconformance might be caused e.g. by an electricity outage or control error.
Information about an elevator car becoming jammed outside the exit floor is usually sent to a service center for the elevators and then onwards to a serviceman, who visits the site to free the passengers stuck in the elevator car.
Freeing the passengers takes place by performing a rescue run from outside the elevator hoistway by opening the mechanical brakes of the hoisting machine from a manual opening handle. After the brakes have been opened the traction sheave of the hoisting machine is able to rotate, in which case the elevator car starts to move from the effect of gravity. If electric power is available from the main supply of the elevator and the electric drive of the elevator is operational, the serviceman can also drive the elevator car at low speed with the hoisting machine from outside the elevator hoistway from a manual user interface equipped for this purpose. The run takes place by depressing and holding down the drive switch in the manual user interface. The serviceman monitors the progress of the elevator car either via direct visual contact or from a separate speed display, and engages the mechanical brakes/releases the drive switch when the elevator car arrives at an exit floor, when the elevator car stops.